Where are all the unaccounted for Salmon?

You've done a great job of tracking the hatchery return component of the Chinook run.  Here are other items that need to be considered in doing a run reconstruction: Mortality between Lower Granite Dam and the hatcheries - there is mortality due to environmental reasons, predators, diseases, injuries, hard angler releases, etc.  We don't know what percentage are actually lost once fish pass Lower Granite but some biologists speculate it could be ~10%. Straying of returning adults.  There is not 100% fidelity in returning adult fish.  Straying rates vary for the different stocks of fish.  Studies show it could be from 5 - 15%.  Hence, these fish are unaccounted for at the hatchery trapping sites. Fish returning to Oregon tributaries above Lower Granite Dam - there are a couple of significant streams in Oregon that contribute to Chinook returns passing Lower Granite Dam. Wild Chinook - your accounting doesn't show a total for wild or natural production that occurs in the Clearwater or Salmon basins. Tribal harvest of the sport fishery - we don't currently have harvest information for the Nez Perce or Shoshone Bannock tribes.  They are not required to provide us their harvest information, so it's not posted on our managed data sites. Late arriving hatchery fish - Chinook, although the numbers are lower, will continue returning to our traps up until they spawn.  There will still be late arriving fish.  There are also Chinook at several of our facilities that never actually enter our traps and will spawn just downstream. As you can probably see, accounting for fish in the wild - and when you have no control over the different variables affecting survival, is extremely difficult.  There is an element of making educated "guesses" when it comes to accounting for all the fish.  We often error on the side of being conservative in our harvest estimates so we can assure enough brood stock to provide fishing in future years.